package service

import (
	"context"
	"errors"
	"fmt"
	"os"
	"path/filepath"
	"strings"

	"github.com/truewhile/MeBox/internal/model"
)

type LibraryRootInput struct {
	ID        string `json:"id,omitempty"`
	Name      string `json:"name,omitempty"`
	Path      string `json:"path"`
	Enabled   *bool  `json:"enabled,omitempty"`
	SortOrder *int   `json:"sort_order,omitempty"`
}

// CreateLibrary persists a library after validating that its path exists.
func (s *MediaService) CreateLibrary(ctx context.Context, name, path, kind string) (*model.Library, error) {
	return s.CreateLibraryWithRoots(ctx, name, kind, []LibraryRootInput{{Path: path}})
}

func (s *MediaService) CreateLibraryWithRoots(ctx context.Context, name, kind string, inputs []LibraryRootInput) (*model.Library, error) {
	return s.CreateLibraryWithRootsAndCover(ctx, name, kind, "", inputs)
}

func (s *MediaService) CreateLibraryWithRootsAndCover(ctx context.Context, name, kind, coverURL string, inputs []LibraryRootInput) (*model.Library, error) {
	if strings.TrimSpace(name) == "" {
		return nil, errors.New("name required")
	}
	roots, err := normalizeLibraryRootInputs(inputs, true)
	if err != nil {
		return nil, err
	}
	kind = inferLibraryKind(name, roots[0].Path, kind)
	if existing, err := s.findLogicalLibrary(ctx, name, kind); err != nil {
		return nil, err
	} else if existing != nil {
		if strings.TrimSpace(coverURL) != "" {
			if err := s.UpdateLibraryCover(ctx, existing.ID, coverURL); err != nil {
				return nil, err
			}
		}
		lib, err := s.appendLibraryRoots(ctx, existing, roots)
		if err != nil {
			return nil, err
		}
		s.invalidateMediaCache(ctx)
		return lib, nil
	}
	lib := &model.Library{
		Name:            strings.TrimSpace(name),
		Path:            roots[0].Path,
		Type:            kind,
		CoverURL:        strings.TrimSpace(coverURL),
		Enabled:         true,
		CarouselEnabled: false,
	}
	if err := s.repo.Library.CreateWithRoots(ctx, lib, roots); err != nil {
		return nil, err
	}
	s.invalidateMediaCache(ctx)
	return lib, nil
}

// CreateLibrariesPerSubfolder 为 parent 目录下的每个直接子目录各建一个媒体库，
// 媒体库名取子目录名，路径指向该子目录。kind 为空时按子目录名推断类型。
func (s *MediaService) CreateLibrariesPerSubfolder(ctx context.Context, parent, kind, coverURL string) ([]model.Library, error) {
	parent = strings.TrimSpace(parent)
	if parent == "" {
		return nil, errors.New("parent path required")
	}
	dir, err := resolveAccessibleLibraryPath(parent)
	if err != nil {
		return nil, err
	}
	entries, err := os.ReadDir(dir)
	if err != nil {
		return nil, fmt.Errorf("read directory failed: %w", err)
	}
	subdirs := make([]string, 0, len(entries))
	for _, entry := range entries {
		if !entry.IsDir() {
			continue
		}
		if strings.HasPrefix(entry.Name(), ".") {
			continue
		}
		subdirs = append(subdirs, filepath.Join(dir, entry.Name()))
	}
	if len(subdirs) == 0 {
		return nil, errors.New("no subfolders found")
	}
	created := make([]model.Library, 0, len(subdirs))
	for _, subdir := range subdirs {
		name := filepath.Base(subdir)
		lib, err := s.CreateLibraryWithRootsAndCover(ctx, name, kind, coverURL, []LibraryRootInput{{Path: subdir}})
		if err != nil {
			return nil, fmt.Errorf("create library for %s: %w", subdir, err)
		}
		created = append(created, *lib)
	}
	return created, nil
}

func (s *MediaService) UpdateLibraryCover(ctx context.Context, libraryID, coverURL string) error {
	return s.repo.DB.WithContext(ctx).Model(&model.Library{}).Where("id = ?", libraryID).
		Update("cover_url", strings.TrimSpace(coverURL)).Error
}

// UpdateLibraryFields updates sort_order / carousel_enabled on a library.
func (s *MediaService) UpdateLibraryFields(ctx context.Context, libraryID string, sortOrder *int, carouselEnabled *bool) error {
	updates := map[string]any{}
	if sortOrder != nil {
		updates["sort_order"] = *sortOrder
	}
	if carouselEnabled != nil {
		updates["carousel_enabled"] = *carouselEnabled
	}
	if len(updates) == 0 || strings.TrimSpace(libraryID) == "" {
		return nil
	}
	return s.repo.DB.WithContext(ctx).Model(&model.Library{}).
		Where("id = ?", libraryID).Updates(updates).Error
}

// ReorderLibraries persists a full media-library ordering.
func (s *MediaService) ReorderLibraries(ctx context.Context, ids []string) error {
	return s.repo.Library.SetSortOrder(ctx, ids)
}

func (s *MediaService) findLogicalLibrary(ctx context.Context, name, kind string) (*model.Library, error) {
	if s == nil || s.repo == nil || s.repo.Library == nil {
		return nil, nil
	}
	libs, err := s.repo.Library.List(ctx)
	if err != nil {
		return nil, err
	}
	nameKey := strings.ToLower(strings.TrimSpace(name))
	typeKey := strings.ToLower(strings.TrimSpace(kind))
	for i := range libs {
		if strings.ToLower(strings.TrimSpace(libs[i].Name)) == nameKey &&
			strings.ToLower(strings.TrimSpace(libs[i].Type)) == typeKey {
			return &libs[i], nil
		}
	}
	return nil, nil
}

func (s *MediaService) appendLibraryRoots(ctx context.Context, lib *model.Library, roots []model.LibraryRoot) (*model.Library, error) {
	if lib == nil {
		return nil, errors.New("library not found")
	}
	if err := s.ensureLibraryRoots(ctx, lib.ID); err != nil {
		return nil, err
	}
	existing, err := s.repo.Library.ListRoots(ctx, lib.ID)
	if err != nil {
		return nil, err
	}
	for i := range roots {
		root := roots[i]
		root.LibraryID = lib.ID
		root.SortOrder = len(existing) + i
		if err := s.ensureLibraryRootPathUnique(ctx, lib.ID, "", root.Path); err != nil {
			return nil, err
		}
		if err := s.repo.Library.CreateRoot(ctx, &root); err != nil {
			return nil, err
		}
	}
	if err := s.syncLibraryPrimaryRoot(ctx, lib.ID); err != nil {
		return nil, err
	}
	return s.repo.Library.FindByID(ctx, lib.ID)
}

func normalizeLibraryRootInputs(inputs []LibraryRootInput, requirePath bool) ([]model.LibraryRoot, error) {
	roots := make([]model.LibraryRoot, 0, len(inputs))
	seen := map[string]struct{}{}
	for i, input := range inputs {
		rawPath := strings.TrimSpace(input.Path)
		if rawPath == "" {
			if requirePath {
				return nil, errors.New("at least one path required")
			}
			continue
		}
		abs, err := normalizeLibraryRootPath(rawPath)
		if err != nil {
			return nil, err
		}
		key := libraryRootPathKey(abs)
		if _, ok := seen[key]; ok {
			return nil, fmt.Errorf("duplicate library path: %s", abs)
		}
		seen[key] = struct{}{}
		enabled := true
		if input.Enabled != nil {
			enabled = *input.Enabled
		}
		roots = append(roots, model.LibraryRoot{
			Name:    strings.TrimSpace(input.Name),
			Path:    abs,
			Enabled: enabled,
		})
		if input.SortOrder != nil {
			roots[len(roots)-1].SortOrder = *input.SortOrder
		} else {
			roots[len(roots)-1].SortOrder = i
		}
	}
	if len(roots) == 0 && requirePath {
		return nil, errors.New("at least one path required")
	}
	return roots, nil
}

func (s *MediaService) ListLibraryRoots(ctx context.Context, libraryID string) ([]model.LibraryRoot, error) {
	if err := s.ensureLibraryRoots(ctx, libraryID); err != nil {
		return nil, err
	}
	return s.repo.Library.ListRoots(ctx, libraryID)
}

func (s *MediaService) AddLibraryRoot(ctx context.Context, libraryID string, input LibraryRootInput) (*model.LibraryRoot, error) {
	lib, err := s.repo.Library.FindByID(ctx, libraryID)
	if err != nil {
		return nil, err
	}
	if lib == nil {
		return nil, errors.New("library not found")
	}
	roots, err := normalizeLibraryRootInputs([]LibraryRootInput{input}, true)
	if err != nil {
		return nil, err
	}
	root := roots[0]
	root.LibraryID = libraryID
	if err := s.ensureLibraryRootPathUnique(ctx, libraryID, "", root.Path); err != nil {
		return nil, err
	}
	if root.SortOrder == 0 {
		existing, _ := s.repo.Library.ListRoots(ctx, libraryID)
		root.SortOrder = len(existing)
	}
	if err := s.repo.Library.CreateRoot(ctx, &root); err != nil {
		return nil, err
	}
	if strings.TrimSpace(lib.Path) == "" {
		_ = s.repo.DB.WithContext(ctx).Model(&model.Library{}).Where("id = ?", libraryID).Update("path", root.Path).Error
	}
	return &root, nil
}

func (s *MediaService) UpdateLibraryRoot(ctx context.Context, libraryID, rootID string, input LibraryRootInput) (*model.LibraryRoot, error) {
	root, err := s.repo.Library.FindRootByID(ctx, libraryID, rootID)
	if err != nil || root == nil {
		return root, err
	}
	updates := map[string]any{}
	if input.Name != "" {
		updates["name"] = strings.TrimSpace(input.Name)
	}
	if strings.TrimSpace(input.Path) != "" {
		roots, err := normalizeLibraryRootInputs([]LibraryRootInput{input}, true)
		if err != nil {
			return nil, err
		}
		if err := s.ensureLibraryRootPathUnique(ctx, libraryID, rootID, roots[0].Path); err != nil {
			return nil, err
		}
		updates["path"] = roots[0].Path
		root.Path = roots[0].Path
	}
	if input.Enabled != nil {
		updates["enabled"] = *input.Enabled
		root.Enabled = *input.Enabled
	}
	if input.SortOrder != nil {
		updates["sort_order"] = *input.SortOrder
		root.SortOrder = *input.SortOrder
	}
	if err := s.repo.Library.UpdateRoot(ctx, root, updates); err != nil {
		return nil, err
	}
	if err := s.syncLibraryPrimaryRoot(ctx, libraryID); err != nil {
		return nil, err
	}
	return s.repo.Library.FindRootByID(ctx, libraryID, rootID)
}

func (s *MediaService) DeleteLibraryRoot(ctx context.Context, libraryID, rootID string) error {
	root, err := s.repo.Library.FindRootByID(ctx, libraryID, rootID)
	if err != nil {
		return err
	}
	if root == nil {
		return errors.New("library root not found")
	}
	roots, err := s.repo.Library.ListRoots(ctx, libraryID)
	if err != nil {
		return err
	}
	if len(roots) <= 1 {
		return errors.New("library must keep at least one path")
	}
	if err := s.repo.Media.DeleteByLibraryRoot(ctx, libraryID, rootID); err != nil {
		return err
	}
	if err := s.repo.Library.DeleteRoot(ctx, libraryID, rootID); err != nil {
		return err
	}
	return s.syncLibraryPrimaryRoot(ctx, libraryID)
}

func (s *MediaService) ensureLibraryRoots(ctx context.Context, libraryID string) error {
	lib, err := s.repo.Library.FindByID(ctx, libraryID)
	if err != nil || lib == nil || len(lib.Roots) > 0 || strings.TrimSpace(lib.Path) == "" {
		return err
	}
	root := &model.LibraryRoot{
		LibraryID: libraryID,
		Name:      libraryRootNameForPath(lib.Path),
		Path:      lib.Path,
		Enabled:   lib.Enabled,
		SortOrder: 0,
	}
	return s.repo.Library.CreateRoot(ctx, root)
}

func (s *MediaService) syncLibraryPrimaryRoot(ctx context.Context, libraryID string) error {
	roots, err := s.repo.Library.ListRoots(ctx, libraryID)
	if err != nil || len(roots) == 0 {
		return err
	}
	return s.repo.DB.WithContext(ctx).Model(&model.Library{}).Where("id = ?", libraryID).Update("path", roots[0].Path).Error
}

func (s *MediaService) ensureLibraryRootPathUnique(ctx context.Context, libraryID, exceptRootID, pathValue string) error {
	roots, err := s.repo.Library.ListRoots(ctx, libraryID)
	if err != nil {
		return err
	}
	key := strings.ToLower(filepath.Clean(strings.TrimSpace(pathValue)))
	key = libraryRootPathKey(pathValue)
	for _, existing := range roots {
		if existing.ID == exceptRootID {
			continue
		}
		if libraryRootPathKey(existing.Path) == key {
			return fmt.Errorf("duplicate library path: %s", pathValue)
		}
	}
	return nil
}

func normalizeLibraryRootPath(rawPath string) (string, error) {
	rawPath = strings.TrimSpace(rawPath)
	return resolveAccessibleLibraryPath(rawPath)
}

func libraryRootPathKey(pathValue string) string {
	pathValue = strings.TrimSpace(pathValue)
	return strings.ToLower(filepath.Clean(pathValue))
}

func libraryRootNameForPath(pathValue string) string {
	return filepath.Base(filepath.Clean(pathValue))
}